Pressure-control valve for salvage operations and the like



Nov. 3, 1959 M. MULICK 2,911,003

PRESSURE-CONTROL VALVE FOR SALVAGE OPERATIONS AND THE LIKE Filed Feb. 3, 1955 INVENTOR. MKHAEL MUL/CK United States Patent PRESSURE-CONTROL VALVE FOR SALVAGE OPERATIONS AND THE LIKE Michael Mulick, Lodi, NJ. Application February 3, 1955, Serial No. 485,852 1 Claim. (Cl. 137-508) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The present invention pertains to the art of valves, and particularly to the art of pressure-control valves. The valve of the invention is particularly useful in marine salvage operations.

The present invention is embodied in a valve structure that permits fluid flow between the interior and exterior of a pressure-fluid container in response to a predetermined pressure dilferential between the interior and exterior of the container. The invention is useful, for example, in the type of pressure-fluid drum that is used for submarine salvage of ships and the like.

When a sunken ship is located at the bottom of a body of water, and it is desired to raise the vessel, under wellknown salvage practice a pressure-fluid container in the form of a drum is lowered to the ship and attached thereto securely. Usually several such drums are employed, to afford a sufficient total volume for the'required buoyancy. Under practice of salvage operations that are well known, water is contained in the drums to submerge them to the level of the sunken vessel, and after the drums are secured to the sunken vessels, buoyancy gas is pumped into each of the one or more buoyancy drums, to drive the water out and render them buoyant, until they are sufficiently buoyant to raise the ship from the bottom. Usually compressed air is used for the purpose.

When the drums attain a buoyancy that is sufficient to raise the sunken vessel, the vessel with the drums attached thereto travel upwardly towards the surface of the body of water. Usually the sunken vessel is held down by suction in addition to its weight, and an accumulation of silt may be present. When the sunken vessel with the drums attached thereto rises to a higher level in the water, the pressure differential between the interior of the drums and the ambient water exteriorly of the drums increases, and as the operation of raising the sunken vessel progresses towards the surface, the lifting force becomes progressively greater than is needed to lift the vessel. Accordingly, the speed of the vessel travelling upwardly is accelerated.

Therefore, as the operation of raising the vessel progresses, it is common practice to reduce the lifting force progressively to prevent the vessel from being lifted too rapidly. Accordingly, under existing practice the fluid pressure in the buoyancy drums is varied from time to time as a compensating adjustment of buoyancy for the level at which the vessel is located at different times during the operation. These controls are adjusted at the surface station, usually by manual means.

Sometimes buoyancy balance gets out of hand, nevertheless, due to the buoyancy force that is required to break the sunken vessel away from the bottom, followed by the lifting force increasing constantly beyond what is needed for raising the sunken vessel as it approaches the surface. There have been occasions when the sunken vessel breaks 2,911,003 Patented Nov. 3, 1959 ICC the surface at a speed sufficient to cause it to be thrown out of the water.

The present invention is embodied in a valve, one at least of which is secured to each of the several buoyancy drums. The novel valve operates automatically to release the pressure within a buoyancy drum in response to changing pressure differential between the interior and exterior of the drum, whereby the buoyancy of the drum diminishes progressively in accordance with the pressure change of ambient water exteriorly of the drum.

A fuller understanding of the principles of the invention, and one practical embodiment thereof, is presented in the accompanying drawing, in which Fig. l is an axial cross-sectional elevation of a valve embodying the present invention, and

Fig. 2 is a cross-section, taken on line 2--2 of Fig. 1.

Container 11 embodies any structure that will serve as a buoyancy drum suitable for salvage operations, and comprises a valve 12 secured to the outside surface of the drum, as shown.

A drum 11 for salvage operations usually is cylindrical, and according to usual practice comprises lugs or the like attaching devices on its outer surface, and located in predetermined positions to receive shackle structure by means of which the drum is secured to a sunken ship or the like in predetermined position with reference thereto. Hose connections are also located on the outer surfaces of the drum in predetermined positions, by means of which the fluid pressure within the drum is controlled. The attaching devices and hose connections are located in predetermined positions with reference to each other to position the hose lines where they will not become fouled during a salvage operation with the sunken ship, or any portion of the salvaging gear. These considerations are well within the purview of prior-art salvaging practices, and will vary under different circumstances. For these reasons structure thereof is not included in the present disclosure, which is limited to the novel valve structure 12 of the present invention.

Valve 12 comprises the flexible wall 15, which is movable to collapse or expand respectively towards and away from container or drum 11, in response to varying pressure differential between the interior and exterior of drum 11. Flexible wall 15 is secured at its one end to drum 11 by means of the attaching ring 16. Rigid wall 17 is secured to the other end of flexible wall 15 remote from container 11, to complete the closure of the chamber consisting of the walls 15 and 17, attaching ring 16 and the plate of drum 11. All connections, between walls 17 and 15, between wall 15 and ring 16, and between ring 16 and drum 11, are fiuidtight.

Interiorly of the chamber of valve 12, the plate of drum 11 is perforated at 18, to permit fluid to pass freely between drum 11 and the chamber of walls 15 and 17, and the chamber and drum are constantly under the same fluid pressure.

Cylindrical valve stem 20 is secured rigidly to the plate of drum 11, and projects into and through the chamber of valve 12, and through an aperture in the rigid wall 17 thereof. Wall 17 comprises the gasket 21, which is contained in the aperture of wall 17, and which fits tightly around the cylindrical portion 22 of stem 20, thereby forming a seal that prevents fluid flow between the inside and outside of drum 11 through the valve 12. Cylindrical portion 22 of stem 20 extends for a distance along its length. Adjacent to the cylindrical portion 22, stem 20 comprises a reduced portion 23, which is tapered extending from cylindrical portion 22 to the end of the stem. At the reduced portion or taper 23, gasket 21 fits loosely around stem 20, and permits fluid flow through the aperture of wall 17 of the chamber, in the direction determined by the pressure differential between fluid inside drum 11 and ambient fluid exteriorly thereof.

Rigid wall 17 is under a force that urges it constantly towards drum 11, in the direction to collapse flexible wall 15 and reduce its volume to a minimum. Such force comprises the weight of rigid wall 17 and the fluid pressure of the fluid exterior drum 11. The gasket 21 thereby is located along cylindrical portion 22 of valve stem 20, in which position the chamber is sealed against fluid flow either into or out of drum 11. As structure that is particularly useful for salvage operations, valve 12 is located peripherally of drum 11 where it is positioned at its upper surface when the drum is secured to a submerged vessel or the like, which is to be raised by buoyancy of the drum. This positions valve 12 above the level of any water that is contained in drum 11.

For use in a salvage operation, drum 11 is lowered in the body of water to a position adjacent to the submerged vessel, and is secured thereto. To lower drum 11, water is pumped into it to reduce its buoyancy until it sinks. After drum 11 is secured to the sunken vessel, air is pumped into the drum to increase its buoyancy, under pressure that is suflicient to eject water contained in the drum outwardly into the ambient water exteriorly of the drum. For most salvage operations, usually several drums 11 are secured to a sunken vessel that is to be raised, at difierent positions around it, and air under pressure is pumped into each. The air is pumped into the several drums until their cumulative buoyancy is suflicient to lift the sunken vessel away from the bottom. All this is wellknown prior-art salvage practice.

The suction and accumulation of silt which, in addition to the weight of the sunken vessel, holds it at the bottom, may resist the buoyancy forces that are required to raise the vessel otf of the bottom sufficiently to require a buoyancy build-up that is difficult to keep under control after the vessel has started upwardly to the surface. This buoyancy control is retained more easily and with greater certainty by means of the valve of the present invention.

When drum 11 is submerged and secured to a sunken vessel, rigid wall 17 is positioned along stem 20 near the plate of drum 11, where its gasket 21 is along cylindrical portion 22 of the stem. The weight of rigid wall 17 is suflicient for the purpose, and a wall 17 of sufl'icient weight is selected to meet the conditions expected to be encountered in the particular salvage operation. Valve 12 being at the uppermost position of the drum, rigid wall 17 sinks of its own weight along stem 20 towards drum 11. The pressure of ambient water exteriorly of drum 11 at the position of submergence also operates to press rigid wall 17 towards drum 11.

When air is pumped into a drum 11 to eject water that it contains, the pressure dilferential changes between the fluid interiorly of drum 11 and the ambient fluid exteriorly. The pressure is higher inside drum 11, and inside the chamber of valve 12, when sufficient buoyancy is established to raise the vessel. The higher pressure in drum 11 causes the chamber of valve 12 to expand. Flexible wall 15 is extended, and rigid wall 17 travels along the stem 20. The weight of rigid wall 17 is sulficient for gasket 21 to engage cylindrical portion 22 at a position approaching tapered portion 23 at the time when the sunken vessel starts to rise. As soon as the sunken vessel reaches a depth at which the decreasing pressure of ambient water exteriorly of drum 11 produces a pressure differential high enough for gasket 21 to engage tapered portion 23 of valve stem 20, air escapes from the drum into the water exteriorly thereof. The result is a pressure drop inside drum 11, which continues until gasket 21 again engages the cylindrical portion 22 of valve stem 26, and escape of compressed air from the drum is stopped.

Valve 12 operates as a control which is auxiliary to the usual controls that are operated to maintain a correct buoyancy balance in drums 11, and valve 12 operates automatically to enable buoyancy control to be maintained more easily and certainly.

The disclosed structure is one practical embodiment of the invention.

What is claimed is:

A valve structure for controlling the pressure of fluid in a container having a perforated plate portion, said valve structure comprising a ring adapted to be secured to said plate over such plate portion, a flexible wall member secured to and extending from said ring, a rigid wall member comprising a disc-shaped weight, said rigid wall member being secured to the edge of said flexible wall member that is distal said ring, whereby said ring and said wall members are adapted to provide, with such perforated plate portion, an expansible chamber, a gasket secured centrally in said rigid wall member, and a cylindrical valve stem having a base adapted to be secured to such plate portion, said valve stem having a cylindrical portion of uniform diameter extending from such base through said gasket, said valve stem and gasket thereby providing a fluid-tight seal, said valve stem further having a tapered portion extending from said cylindrical portion to the end of said valve stem distal said base, said end being of lesser diameter than the diameter of said portion of uniform diameter, whereby flexing of said flexible wall member to move said rigid wall member away from such plate moves said gasket to a position upon said tapered portion and thereby breaks the seal between said valve stem and gasket.

References Cited in the file of this patent UNITED STATES PATENTS 274,512 OReilly Mar. 27, 1883 780,986 Francis Jan. 31, 1905 1,199,152 Bruce Sept. 26, 1916 1,766,554 Sieber June 24, 1930 1,911,561 Fitts May 30, 1933 2,412,205 Cook Dec. 10, 1946 2,451,002 Sturtevant Oct. 12, 1948 2,594,626 Earle Apr. 29, 1952 FOREIGN PATENTS 423,921 Great Britain Nov. 13, 1933 872,910 Germany Apr. 13, 1953 896,463 Germany Nov. 12, 1953 

